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Epochal changes in the seasonal evolution of tropical Indian Ocean warming associated with El Niño

Chakravorty, S and Chowdary, JS and Gnanaseelan, C (2014) Epochal changes in the seasonal evolution of tropical Indian Ocean warming associated with El Niño. Climate Dynamics, 42 (3-4). pp. 805-822.

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Abstract

The epochal changes in the seasonal evolution of El Niño induced tropical Indian Ocean (TIO) warming in the context of mid-1970s regime shift is investigated in this study. El Niño induced warming is delayed by one season in the northern TIO during epoch-2 (post mid-1970) and southern TIO during epoch-1 (pre mid-1970). Significant spatiotemporal changes in TIO (especially in the north) warming are apparent during the developing phase of El Niño. The ocean dynamics is the major driver in the basin wide warming during epoch-2 whereas heat fluxes are the dominant processes during epoch-1. Strong coupling between thermocline and sea surface temperature (SST) in epoch-2 indicates that El Niño induced oceanic changes are very significant in the seasonal evolution of basin-wide warming. The thermocline-SST coupling is strengthened by the upward propagating subsurface warming in epoch-2. The westward propagating barrier layer over southern TIO supports persistence of warm SST (over southwest TIO in epoch-2), which in turn induce spring asymmetric mode in winds and precipitation. The asymmetric wind pattern and persistent subsidence over maritime continent are primarily responsible for stronger spring warming in epoch-2. The strong east equatorial Indian Ocean cooling in epoch-2 is mainly driven by coastal upwelling over Java-Sumatra coast, whereas in epoch-1 the weak cooling is controlled by the latent heat flux. The spatiotemporal changes in TIO SST warming and their evolution have strong impact on atmospheric circulation and rainfall distribution over the Indian Oceanic rim through local air-sea interaction.

Item Type: Article
Additional Information: Copyright of this article belongs to Springer.
Uncontrolled Keywords: ENSO;Indian Ocean Dipole;Tropical Indian Ocean;Climate shift;Rossby waves;Thermocline-SST coupling
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 04 Dec 2014 09:32
Last Modified: 04 Dec 2014 09:32
URI: http://moeseprints.incois.gov.in/id/eprint/927

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